Safety switch



Patented Sept. 27, 1921.

UNITED? STATES PATENT OFFICE-.8

HARRISON J. L- FRANK, OF DETROIT, MICHIGAN, ASSIGNOR TO MUTUAL ELECTRIC AND MACHINE COMPANY, OK DETROIT, MICHIGAN, A CORPORATION OF WEST VIR- GINIA.

SAFETY SWITCH.

Application filed May 5, 1922. Serial No. 558,578.

This invention relates to safety switches which comprise boxes in which the circuit closin devices are mounted and in which such evices are inaccessible so long as the circuit is closed, and the object of this invention is to provide a safety switch embodying removable fuses which shall be simple in construction, which can be made at comparatively low cost, in which the fuses are accessible only after the circuits are broken, and in which the cover which gives access to the fuses must be closed before the circuits can be closed.

I This invention consists in the details of construction illustrated in the accompanying drawings and particularly pointed out in the claims.

In the drawings, Fig. 1 is a side elevation of this improved safety switch. Figs. 2 and 3 are sections on the lines 2-2 and 33 of -Fig. 1 respectively. Fig. 4 is a section on line 44 of Fig. 2 with the fuse shown in elevation. Fig. 5 is a section on line 5-5 of Fig. 2 with the fuse omitted. Figs. 6 and 7 are sections on the lines 6-6 and77 of Fig. 3 respectively. Fig. 8 is another side elevation of the switch with a slightly modified cover. Fig. 9 is a section of the pivotal mounting of the operating handle. Fig. 10

is a section on the line 1010 of Fig. 8.

Similar reference characters refer to like parts throughout the several views.

The box shown in the drawings is preferably of metal and comprises a bottom 1, sides 2 and 3, ends 4 and 5, the latter preferably havin an o ening 46 for. wires, and the cover 8, t e part 8 being secured to the box in any desired manner, as by the screws 1 9, (Fig. 6) and the part 7 bein hinged to the'part 8. Within the box an secured to the sides 2 and 3 thereof by means of brackets 11 is a slab 10 of slate or other good insulating material.

A pair of disks 15 and 16, on opposite sides of the side 2, are secured together by the screws 56. It is usually difiicult to permanently journal a shaft or other rotatable member in a sheet of nietal, but I overcome this difliculty by forming the hole in the side '2 (lite large and by securing a third disk 57 tween the disks 15 and 16 by means of the screws 56, as shown in Fig. 9. These screws preferably pass through the handle 17 and into the bail 52. To these disks is secured the operating handle 17. One end 18 of the handle 17 extends over the cover to the side 2 of the box.

Mounted on one side of the slab 10 are fuse clips 24, 25, 26 and 27 and on the other side is a knife blade switch consisting of the pedestals 28 and 29 between which the knife blades 31' and 32 are pivoted, and the clips 33 and 34. The arrangement of these clips and switches is so much a matter of choice that the parts shown in the drawing may be taken merely as an example. The line wires 35 and 36 may connect to the pedestals 28 and 29 b means of nuts 37, and when the circuit is c osed, the current will pass over the blades 31 and 32, clips 33 and 34, bolts 38 through the slab to the fuse clips 24 and 25, thence through fuses 39 and 40 to the fuse clips 26 and 27, and bolts 42 through the slab to the load wires 43 and 44 which are secured in place by the nuts 45. This permits all the load and line wires to ass through the hole 46 in the end 4 of the ox.

A bar 47 of insulating material connects the knife blades 31 and 32 and connected thereto is a bracket 48 (Fig. 6) which carries the shield 49, also preferably of insulati'ng material. A book 50 extends from the bar 47 and engages the bail 52 which is con- .nected to the disks 15 and 16 and to the handle 17, so that the knife blades 31 and 32 may be swung into or out of engagement. with the clips 33 and 34 by the handle 17 without the box being opened. While the handle is normally held in the closed-circuit position by the latch, a spring 58 on the screw 59 as shown in Fig. 7 normally tends to-swing the bail and lever back to the position shown in dotted lines in Fig. 6, and this movement is caused by the spring as soon as 4 the latch releases the handle.

The cover 7-8 is preferabl a section of a cylinder with the center of t e cylinder coaxial with the axis of the bail 52 and handle 17 As stated before, a part 18 of the handle 17 extends over the cover and the result is that when the handle is moved to the position indicated in Fig. 1 the part 7 of the cover cannot be lifted, nor can the handle be swung to circuit closing position until the cover has been swung back to the position shown in solid lines in Fig. 1.

The slab 10 of slate or other non-conducting material can be made very small, that is, not over one-half of the ordinary size necessary in switch boxes where the slab forms the bottom of the box. In the present case the switch proper is on one side of the slab and the fuse on the other and the slab is upright in the box when it rests on its bottom and divides the box into two compartments. This location of the slab not only saves material, but it permits direct connection through the slab between the clips and fuse holders so that the same bolts will act as -electrical connectors and will secure the arts in position.

The shield 49, referably of non-conducting material suc as vulcanite or gutta percha, is of such length, as indicated in Fig. 6, that at no time can fingers be inserted between the shield and the upper part of the slab 10, and it always extends into the s ace between the top of the slab 10 and the hinge of the cover. As this space need not be over one-quarter inch deep, it is impossible to insert the fingers to touch the knife blades 31 and 32.

In Figs. 8 and 10 a slightly'modified construction of box is shown. The sides, endsand bottom of the box are the same as before described and the part 8 of the cover may also be of the same construction as that shown in Fig. 1. The part 70 of the cover, however, is shown formed with a flange 71 which is a segment of a cylinder whosecenter when this cover is down is the axis of the handle 72. This handle is provided with a pin 73 which extends inwardly over this flange 71 and thereby prevents the cover 70 from being swung open until the handle has been swung to the left in Fig. 8 to opencircuit position.

In order to prevent the cover 70 from being swung too far, a small bracket or projection 74 is secured thereon to engage the part 8 of the cover and thus prevent the part from being swung back so far that the flange 71 will be moved out of the path of the pin 73, for otherwise the handle could be swung forward with-its pin 73 passing beneath the flange 71. In the present case the box must be closed before the handle can be swung forward to close the electric circuit and the handle must be swun back to open the circuit before the box can e opened to give access to the fuses. In both cases the fuses can be safely removed as soon as the movable portion of the cover is out o the way to give admission, for in both cases this part of the cover cannot be swun to open position until the circuit has een opened.

It will be understood that the details of this construction may all be modified by those skilled in the art without departing from the spirit of my invention.

I claim 1. The combination of a box, a stationary slab of non-conducting material dividing the interior of said box into two compartments, a fuse mounted on one side of the slab in one compartment and a switch mounted on the other side of the slab in the other compartment, a manually operable handle pivotally mounted on one side of the box, means within the box connecting the handle to the switch, and a cover for the two compartments of the box comprising a segment of the cylinder whose axis coincides with that of said handle.

2. The combination of a box, a stationary slab of non-conducting material dividing the interior of said box into two compartments, a fuse mounted on one side of the slab in one compartment and a switch mounted on the other side of the slab in the other compartment, a manually operable handle pivotally mounted on one side of the box and means within the box connecting the handle to the switch, and a two part cover for the box comprising a segment of the cylinder whose axis coincides with that of said handle, each of the compartments being closed by a different part of thecover. said handle having a lateral extension substantially parallel to its axis and projecting over said cover.

3. The combination of a box. a stationary slab of non-conducting material dividing it into two compartments, a fuse mounted on one side of the slab in one compartment and a switch mounted on the'other side of the slab in the other compartment, a manually operable handle pivotally mounted on one side of the box and means within the box connecting the handle to the switch, a cover for the box comprising a segment of the cylinder whose axis coincides with that of said handle, and a cylindrical shield connected to said means and movable thereby between said slab and cover.

4. The combination of a box, a stationary slab of non-conducting material substantially midway of the box dividing it into two compartments, a fuse mounted on one side of the slab in one compartment and a switch mounted on the other side of the slab in the other compartment, a manually operable handle pivotally mounted on one side of the box, means within the box connecting the handle to the switch, a cover for the two compartments of the box comprisin a se ment of a cylinder whose axis coinci es wit i that of said handle, means to hold the handle in circuit closing position, and a sprln'g to move the handle to open circuit position, said handle having an extension substantially parallel to its axis and extending over said cover to prevent the cover being opened when the swltch is closed.

5. The combination of a box, a stationary slab of non-conducting material dividing it into two compartments, fuses mounted on one side of the slab in one compartment and a switch mounted on the other side of the slab in the other compartment, means connecting the fuses to said switch electrically and also securin parts of the switch and the fuses to the sla a manually operable handle pivotally mounted on one side of the box, a bail -with1n the box connecting the handle to the switch, a cover for the box comprising a segment of a cylinder whose axis colncides with that of said handle, means to holdthe handle in circuit closing position, a spring to move the handle to open circuit position,

said handle having an extension substantially parallel to its axis and extendi over said cover, and a cylindrical abiel connected to said bail and movable thereby between said slab and cover.

, HARRISON J. L. FRANK. 

